Immunoglobulin complementarity-determining regions

Raaphorst, F.M., Timmers, E., Renter, M.J.H., et al. (1992). Restricted utilization of germline VH3 genes and short diverse third complementarity-determining regions (CDR3) in human fetal B-lymphocyte immunoglobulin heavy chain rearrangements. Eur. J. Immunol., 22, 247-251. 

Figure 22.25. Schematic illustration of an immunoglobulin IgG. The complex consists of two heavy (H) chains and two light (L) chains. Somatic hypermutation that greatly contributes to antibody diversity occurs in the variable (V) regions of both the heavy and the light chins, especially the complementarity-determining regions (CDR).

Abbreviations used in table MC - Monte Carlo aa - amino acid vdW - van der Waals potential Ig - immunoglobulin or antibody CDR - complementarity-determining regions in antibodies RMS -root-mean-square deviation r-dependent dielectric - distance-dependent dielectric constant e - dielectric constant MD - molecular dynamics simulation self-loops - prediction of loops performed by removing loops from template structure and predicting their conformation with template sequence bbdep - backbone-dependent rotamer library SCMF - self-consistent mean field PDB - Protein Data Bank Jones-Thirup distances - interatomic distances of 3 Ca atoms on either side of loop to be modeled. 

Relate the hypervariable sites of the H and L chains of IgG to the complementarity-determining regions (CDRs) of the immunoglobulin. Describe the function of the constant regions of the H and L chains of IgG. 

Schematic representation of an antibody (IgG) molecule. One antibody molecule has two identical active sites. A light chain is built up from one variable domain (VL) and one constant domain (CL), and a heavy chain from one variable domain (VH), followed by constant domains (CHI, CH2, and CHS). Complementarity determining regions, CDR1-CDR3, vary most significantly among different immunoglobulins and determine the specificity of the antigen-antibody interactions.

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